When a video conference and an audio conference are carried out, as described in Patent Literature 1 “VOICE AND IMAGE CONFERENCE DEVICE” etc., network bands for the number of participants from other bases are needed, and it is difficult to participate in the video conference and the audio conference from the base etc. having a narrow line.
For example, an operation in a case of holding a video conference straddling bases through the Internet is explained using a network connection diagram of FIG. 4 as follows. FIG. 4 is a network connection diagram illustrating a network connection configuration in a case of holding the video conference straddling the bases in a conventional electronic conference system.
In the network connection diagram of FIG. 4, a first exchange system 10A and a second exchange system 20A are connected to each other through an Internet 30. A multi-functional telephone 100 is connected to the first exchange system 10A as a terminal used by a user who is going to organize and hold the video conference, and multi-functional telephones 200 and 201 are connected to the second exchange system 20A as terminals used respectively by two users who are going to participate in the video conference organized by the user of the multi-functional telephone 100 of the first exchange system 10A side.
When three of the multi-functional telephones 100, 200, and 201 carry out the video conference using a video conference mixing device 11A mounted in the first exchange system 10A, first, the multi-functional telephone 100 used by an organizer is connected to the video conference mixing device 11A of the first exchange system 10A, and the multi-functional telephones 200 and 201 used by participants in the video conference are connected to the video conference mixing device 11A of the first exchange system 10A, respectively, via the second exchange system 20A and the Internet 30 without using a video conference mixing device 21A mounted in the second exchange system 20A.
Subsequently, in the video conference mixing device 11A of the first exchange system 10A, conference communication information of audio/Video (video images) from the multi-functional telephone 100, audio/Video from the multi-functional telephone 200, and audio/Video from the multi-functional telephone 201 are mixed, and are distributed to each of the multi-functional telephones 100, 200, and 201, thereby resulting in formation of a video conference network among the three multi-functional telephones.
In such a formation state of the video conference network, as shown in FIG. 4, a state occurs where two sessions of a session 200a for the multi-functional telephone 200 and a session 201a for the multi-functional telephone 201 are formed between the first exchange system 10A and the second exchange system 20A through the Internet 30, and network bands for two multi-functional telephones (audio/Video) are needed.